Animals often show a keen intelligence and many species, from octopuses to crows, can perform problem-solving tasks. But humans are thought to go one step further. We can reflect on our own thoughts and we have knowledge about our knowledge. We can not only solve problems, but we know in advance if we can (or are likely to).

In technical terms, this ability is known as ‘metacognition’. It’s what students do when they predict how well they will do in an exam when they see the questions. It’s what builders do when they work out how long a job will take them to finish. But can animals do the same? Finding out is obviously difficult. No animal is going to tell us what it is thinking. To work that out, we need clever experiments.

Allison Foote and Jonathon Crystal searched for metacognition in rats by giving them a test that they could decline. If they passed, they received a big reward and if they failed, they got nothing. But the cunning part of their study lay in giving the rats a small reward if they declined the test. If they knew they were unlikely to succeed, they’d be better off bowing out. In this experiment, a measured attitude beats a gung-ho one.

The test asked the rat to classify a burst of noise as ‘short’ or ‘long’. Noises that were very short or very long were easy to classify, but those of intermediate length were more challenging. After hearing the noise, the rat was offered two holes through which it could stick its nose – one for accepting the test and one for declining it. If it was up for it, it was then given two levers, one for a short noise, and one for a long one.

After some initial training, the results were clear. The rats were much more likely to opt out of the test if the noise they heard was challenging. And when they accepted the test, they were much more likely to answer correctly than in trials where they were forced to take it. To Foote and Crystal, these results show that the rats knew when they didn’t know the answer. And armed with this knowledge, they could make adaptive choices about their future.

I love experiments like this. They are elegant, clever, and ever so slightly like talking to animals directly. While we’re never going to have Doolittle-style conversations with rats, looking inside their heads (experimentally not literally) is the next best thing. Scientists like Foote and Crystal are like lab-coated rat whisperers.

From the paper’s Summary:”If rats possess knowledge regarding whether they know the answer to the test, they would be expected to decline most frequently on difficult tests and show lowest accuracy on difficult tests that cannot be declined.”
The same thing would happen if the rats learned that hearing an intermediate length sound and sticking their noses in the Accept hole sometimes resulted in not getting food, and hearing the same sound and sticking their noses in the Decline hole always resulted in food. That doesn’t require the rats to engage in metacognition. They may just be declining the test more often in situations where accepting the test increases the risk of not getting food. In other words, they may be evaluating the external situation to determine risk, rather evaluating their internal state to determine knowledge. Possibly what this experiment demontrates is not metacognition, but mixing risky choices with a potentially higher pay off with non-risky choices with a guaranteed low pay off. That would seem to increase the chances of survival, as long as they weren’t risking their lives with the risky choices.
From the paper’s Discussion section: “The rate of declining to take the test increased as the difficulty of the discrimination increased.”
The authors have to assume that the rats are evaluating the difficulty of discrimination in order to justify their conclusions. But if the rats are evaluating risk, where long and short durations are less risky and intermediate durations are riskier, then the authors’ conclusion about metacognition doesn’t follow.
If the rats are engaging in metacognition, then they are doing it as part of risk evaluation (evaluating the risk of not getting food). If they are not engaging in metacognition, then they are still engaging in risk evaluation. By assuming that the rats are evaluating difficulty of discrimination, the authors bias their conclusions. Metacognition and the assumption that the rats are evaluating difficulty of discrimination aren’t necessary to explain the results of the experiment. The simplest explanation is that the rats have evolved the ability to evaluate which behavior is most likely to result in food, along with a tendency to sometimes retest behavior that sometimes results in food.

By assuming that the rats are evaluating difficulty of discrimination, the authors bias their conclusions. Metacognition and the assumption that the rats are evaluating difficulty of discrimination aren’t necessary to explain the results of the experiment.

I think the interpretation of this experiment is wishful on the part of the scientists. It seems far likelier that the rats have learned to classify sounds into short, medium, and long, where short is mapped to right door + left lever, long is mapped to right door + right lever, and medium is mapped to left door.
.. and I can’t prove that my position is right either. There is no unambiguous conclusion that can be drawn from this experiment.

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Ed Yong is an award-winning British science writer. Not Exactly Rocket Science is his hub for talking about the awe-inspiring, beautiful and quirky world of science to as many people as possible.
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